Electronic amplifier with double frequency discriminator



Sept. 1, 1953 R. R. CHAPMAN ELECTRONIC AMPLIFIER WITH DOUBLE FREQUENCYDISCRIMINATOR Filed March 24, 1949 IN V EN TOR. ROBERT R. CHAPMANPatented Sept. 1, 1953 UNITED STATES PATENT OFFICE ELECTRONIC AMPLIFIERWITH DOUBLE FREQUENCY DISCRIMINATOR Delaware Applica on arch 2 1 Seriale- 83 16 17 Claims.

This invention relates to electronic amplifiers and particularly toamplifiers adapted for use in control systems of the type wherein adevice operating at one power supply frequency is controlled inaccordance with electrical signals whose frequencies may be the same ordifferent than the supply frequency.

The present invention arose from the necessity of usin either a fluxgate compass of the type disclosed in the Purves et al. Patent 2383360or a flux valve compass, either of which is utilized to control aircraftequipment such as m tors. Because of the relatively small output of thecompass, it is desirable to employ an mplifier between the compass andthe motor for controlling the same. These flux gate and flux valvecompasses have an output voltage of twice the frequency of the supplyvoltage so that difficulties ar encountered in attempting to use thesame periodically varying power supply for the compass, the amplifierand the motor.

Where it is desired to also use an anti-hunting signal in controllingthe motor, the problem becomes even more difficult since suchanti-hunting signals are generally of the same frequency as the powersupply for the motor. Thus, it is necessary to provide an amplifierwhich is cape aole of causing operation of a controlled motor when thesignals thereto comprise a signal having a frequency that is the same asthe power source energizing the motor and a signal which is of afrequency other than that of the power source.

It is therefore an object of the invention to provide an amplifiercapable of utilizing equipment designed for a particular frequency tooperate under the control of a signal of twice that frequency.

Another object of the invention is to provide an arrangement in which amotor opera-ted with current of a first frequency is controlled -by twosignals, one of the first frequency and the other of a second frequency.

A further object of the invention is :to provide an arrangement such asset forthin the immediately preceding object in which the signal of thefirst frequency is produced -.by operation of the motor for anti-huntingpurposes.

A still further'object is .to provide an arrangement in which a compasshaving a relatively high frequency signal output controls a motoroperated with current of a lower frequency.

A still further object is to provide such an art.- rangement in whichthe motor is further controlled by the signal output ,of a velocitygenerator driven y he m t and havin a ecurrent.

quency the same-as that of the motor energizing Still another object ofthe present invention is to provide an amplifier which is phasediscriminating at a fundamental frequency and at a frequency which is aharmonic thereof.

A still further object of the present invention is to provide anamplifier of the type set forth in the immediately preceding objectwhich controls a motor operating at the fundamental fre- ,quency.

These and other objects. of the present invention will be understoodupon a consideration of th following specification, claims and drawing.

The single figure is a diagrammatic showing of the amplifier of thepresent invention as it is associated with a controlled motor it'll anda flux gate compass if]. The amplifier is operative to sense unbalancesignals from the compass and reversibly control the motor assembly it!in accordance with those signals. The op eration of the motor results inadjustment of a portion of the compass for alignment purposes and willoperate until there no longer is an unbalance voltage in the compass.

The flux gate compass Iii has a primary or exciter windin l5, secondaryor pickup coils It, a receiver stator 18 and a receiver rotor is, thelatter two or" which combine to form a synchro transformer. The exciterI5 is energized by a suitable source of power connected thereto by inputlines H and i2 and leads l3 and 14. These input lines lead to a suitablesource of power, for example, a e00 cycle, volt power supply, not shown.The exciter l5 and pickup coils are mounted so as to be intersected bythe earths magnetic field. The excitation from exciter l5 and the earthsmagnetic field produce a varying amount of saturation in thecores ofwindings l depending upontheir position in the earths magnetic field.The saturation in the cores of the coils 16 result in the appearance ofharmonics in the coils with the second harmonic being predominant. Thefundamental frequency is cancelled out because of the position of theexciter with respect to the coils and thus the main output from the,coils it will be ;800 cycles with a 490 cycle excitation voltage onexciter [5. This output voltage from coils it is applied to the r ceiverstator it which will induce a voltage in rotor 18 if it is displacedfrom an electrically balanced or null position. When there is anunbalance signal, it is desired that thelamplifier of t e r nt apparatusdetect this andcause operationLof-the motorassembly 16! which .will,'in

turn, drive the receiver rotor l9 to a null position Where there will beno output from the rotor 59.

One of the output terminals of receiver rotor 19 of compass I isgrounded at terminal H. The other output terminal of the receiver rotorit is connected to grid 20 of tube 2i through lead 22 so that upon an800 cycle signal appearing on rotor I9 there will be an input to tube2!. In addition to a control electrode 20, tube 2! has an anode 23, acathode 24 and a filament, not shown. The cathode 24 is connected toground terminal I! through a resistor 25 to obtain a desired self biason the cathode 24 with respect to grid 26. The 800 cycle input isamplified by tube 2| and the output therefrom is connected between theanode 23 and a grid of tube 3! by a capacitor 26 and a resistor 21. Thepurpose of resistor 21 is to prevent distortion of the signal impressedon the input circuit of tube 3! as it is amplified by the tube. Thistube has in addition to a grid 30, an anode 32, a cathode 33 and afilament heater, not shown. When a signal is impressed on the inputcircuit, a voltage drop results across a grid leak resistor 36 which isconnected between grid 30 and ground through resistor 27. Cathode 33 isconnected to ground through resistor 36, the latter of which has aby-pass capacitor 35 in parallel therewith. If the input signal to grid38 should be of appreciable magnitude the grid may be driven positivewith respect to the cathode and draw grid current. To preventdistortion, the resistor 27, which is a grid current limiting resistor,limits the voltage swing of the grid to predetermined limits. of thistype are well known in the art and form no part of the invention.

A transformer having a primary 3'1, connected to power leads I l and I2through leads til and 4|, has a plurality of secondaries 42, it, 34 and48 supplying power to the amplifier.

Transformer secondary 44 furnishes the power supply for tubes 2! and 3E.The voltage across secondary 44 is rectified by full wave rectifier tube4'! having anodes 45 and 46, a cathode 52 and a filament, not shown,before being impressed across tubes 2| and 3!. The circuit fromtransformer secondary 44 through rectifier tube il for rectifying thevoltage is as follows: from the terminals of transformer secondary 64,through leads and 5|, anodes 45 and d6, cathode 52, lead 69, choke coil6i, capacitor 64, having resistor 62, relay winding 63 and resistor 55in parallel therewith, and lead 55 to a center tap 53 on transformersecondary 44. Resistor 56 has a capacitor 51 in parallel therewith. Thechoke coil '55 is to filter out the A. C. component of the directcurrent in the output from the tube 47 so that a unidirectional voltagewill be present between lead 65 and ground with the voltage being ofsuch polarity that lead 65 will be positive with respect to groundterminal 54. The positive voltage on lead 65 is applied to the anode oftube 2! by a connection through lead 67. and resistor Hi. It is alsoapplied to the anode of tube 3! by a connection including resistor W.The cathodes of each of devices 2! and M are connected to groundterminal [1 through their respective cathode resistors 25 and 34.

It can thus be seen that the full wave rectifier tube 47 in combinationwith transformer secondary 44 is the unidirectional power supplyfurnishing a voltage across the anodes and cathodes of tubes 2! and 3|for the operation of these tubes. Filter capacitors 64 and 51 eliminatean appreciable portion of the ripple of the voltage in the Voltageamplification stages output of the rectifier which might otherwise beapplied to the anodes of the voltage amplification stages.

As has been explained previously, the signal input on the grid of tube2| has a frequency of 800 cycles. With unidirectional voltage impressedacross the anode and cathode, the output from the tube, as a result ofthe signal, will also have a frequency of 800 cycles. This 800 cycleoutput from tube 3! is impressed on a grid 1! of tube '12 through leadsi3 and M, blocking capacitor I5 and lead 18. The output of tube 3! isalso impressed on a grid 16 of a tube 71 through leads [3 and Bi),blocking capacitor ill and lead 32. Since they are connected to the sameoutput from tube 3 i, the phasing on the grids ii and i6 is the same.Tube it has in addition to the control electrode ii, an anode 83, acathode 8d and a filament, not shown. Tube 1'! has, in addition to grid16 an anode 85, a cathode 86 and a filament, not shown. Tubes '72 and Timay, of course, form two halves of a double triode tube.

Cathode 84 of tube i2 is connected to a ground terminal 8'! throughresistors 90 and 9! having a capacitor 92 in parallel therewith. Cathode86 of tube ll is connected to ground terminal 81 through resistors 93and 9 1 having a capacitor 95 in parallel therewith. The capacitor 92 inparallel with the cathode resistors 96 and 9! of tube 72 and capacitor95 in parallel with the cathode resistors 93 and ii of tube H are filtercapacitors and result in the resistors having a direct voltage impressedthereacross, the polarity of which is positive at the respective cathodeconnections and negative at the respective ground connections. Afeedback circuit from the oathode circuit of tube 72 to grid ll of tube72 is connected from cathode 84 through resistors 90 and 9B and lead 18to grid H A feedback circuit from the cathode circuit of tube H to grid16 of tube T] goes from cathode 16 through resistors 93 and 9? and lead82 to grid '56. These feedback circuits are to provide bias for tubes 72and "H and maintain the grids within predetermined limits so thatincreases in control signal over a desired range will cause increases inplate current until a desired point of saturation is reached, whenfurther increase in input signal will cause no increase in tube current.

The anode supply for tubes 12 and ill, which must have an 800 cyclefrequency because the signal is of 800 cycles is obtained from atransformer having a primary E80 and a secondary Nil. Transformerprimary will is connected across the full Wave rectifier tube ll withone terminal of the primary connected to the anodes t5 and c5 throughleads I63, 32 and 55, centertap 53 on transformer secondary 44, theupper and lower halves of transformer secondary M and leads 5!] and 5E.The other terminal of the transformer primary its is connected to theoathode 52 through lead W5, capacitor :04 and lead 68. A capacitor m5 isconnected across transformer primary i M.

The voltage from transformer secondary 44 after being rectified by tubell is a unidirectional voltage having an 800 cycle ripple. This ripplevoltage appearing in the rectifier output, when impressed acrosscapacitors H14 and lot and transformer primary Hlfi connected to form aseries-parallel resonant circuit, is so acted on by this resonantcircuit as to result in an 800 cycle sine wave being impressed acrossthe transformer primary. Capacitor Hi4 also blocks the direct currentoutput from the full wave rectifier to prevent it from flowing throughthe transformer primary winding I I10. I

Transformer secondary IOI is center-tapped to ground at terminal I01.Anodes '83 and 25 of tubes 12 and 11 are connected to opposite terminalsof transformer secondary IIlI through leads III and III respectively.The output of tube 12 is applied to grid H2 of tube II3, by a connectionincluding lead I I4 connected to cathode 84, resistor H5, lead IIS andresistor H1. The output from tube 11 is applied to grid I28 of tube I2I, by a connection traced from cathode 88 of tube 11 through lead I22,resistor I23, lead I24 and resistor I25. Tubes II3 and I2I are shown inthe drawing to be of the thyratron type, though it is to be understoodthat any suitable amplifying device may be used; Thyratrons I I3 and I2!form a direct current discriminator stage. Thyratron II3 has, inaddition to grid II2, an anode I25, a cathode I21 and a filament I28while thyratron I2I has, in addition to grid IZII, an anode I36, acathode I3I and a filament I29. Filaments I28 and-I29 are tied togetherand are energized by transformer secondary 48 through leads I38 and I39.

Series resistors I55 and I51 are connected across leads H5 and I24. Thejunction between resistors I55 and I51 is connected to ground terminal54 through leads I02 and I68 and resistor 55 having the capacitor 51 inparallel therewith. Resistors II1 and I25 are grid current limitingresistors.

Anode I26 of tube H3 is energized from power lead II through lead I32,relay coil I33, having a capacitor I 34 in parallel therewith, and leadI35. Anode I39 of tube I2I is energized from power lead II through leadI36, relay coil I 31, having a capacitor I40 in parallel therewith, andlead I4I. Cathodes I21 and I3I are connected together and are connectedto a ground terminal I42 through a lead I46 and contacts I43 and I44adapted to be shorted by a movable contact I45, the latter of Which isactuated by coil 53. The purpose of the relay contact in this cathodecircuit is to prevent any possible firing of either of the thyratronsuntil the filaments thereof have had an opportunity to heat up. Therelay contacts I 43 and I44 will not make connection with contact I45until the full wave rectifier tube 41 has warmed up and current isflowing therethrough. When the rectifier tube 41 does conduct it willcause energization of relay winding 53 in a circuit that may be tracedfrom transformer secondary 44 through leads 55 and 5! to anodes 45 and46, cathode 52, lead 55, choke coil BI, resistor 62, relay winding 53,resistor 55 and lead 55 to transformer center-tap 53.

Upon operation of rectifier 41 a unidirectional voltage is impressedacross resistor 56 of such polarity that the lower or ground end of theresistor, as positioned in the drawing, will be positive with r spect tothe upper end. The unidirectional voltage on this resistor is applied tothe grids H2 and I25 of tubes H3 and I2I, respectively, as a biasvoltage by a circuit traced from the negative or upper end of resistor56 through leads Hi2 and IE9 to the junction of resistors I 55 and I 51.The resistor I56 is connected to the grid II2 by resistor II1 while theresistor I51 is connectedto the grid I20 by a resistor I25. Resistors I56 and I51 act as summing and isolating resistors to add the negativebias from resistor 55 and the output signal from tubes 12 and 11 tocontrol the current flow in tubes I I3 and I2I without aifectingoperation of tugoes 12 and '11, as will be explained in detail la er.

Relay coil I33 connected in the output circuit of tube H3 operates amovable contact I41 normally biased out of engagement with a pair offixed contacts I55 and I5I, by means not shown. Relay coil I31 connectedin the output circuit of tube I2I operates a movable contact I52normally biased out of engagement with a pair of fixed contacts I53 andI54, by means not shown. A capacitor I55 acts as a phase shiftingcapacitor in the energizing circuit of motor IBI.

The aligning motor I SI has a rotor I52 and field windings I53 and I54.Assuming that movable contact I41 is closed against the fixed contactsI55 and I5I, field winding I33 is connected across the power line leadsII and I2 in a circuit traced from power lead II throughlead I32,

contact I53, movable contact I41, fixed contact I5I, and lead I65 tofield winding I63, ground terminals I55 and 28 to power lead I2. Thefield winding I64 is connected across the power line leads II and I2 ina circuit traced from power lead II through lead I 32, fixed contactI53, movable contact I41, fixed contact I5I, capacitor I55 and lead I 51to field winding I64, ground terminals I55 and 28 to power lead I2. Itis seen that the energizing circuit for field winding I64 passes throughphase shifting capacitor I55 to shift the phase of the energizingvoltage of field winding I64 90 with respect to the energizing voltageof field winding I53 and so cause rotation of rotor I62.

Rotation of rotor Id? of aligning motor I III causes rotation of rotorI19 of velocity generator III since said motor is connected thereto by asuitable mechanical connection I12. Velocity generator I?! has a pair offield windings I13 and IE4. Field winding I13 of velocity generator I1Iis continuously energized from the power source leads II and I2 by acircuit traced from lead II through leads I3 and I16, field winding I13,and leads I'III and I4 to power lead I2. Rotation of rotor I'IG ofvelocity generator ill by motor I5I causes a voltage to be induced infield winding I'I4. This voltage is proportional in magnitude and phaseto the speed and direction of rotation of rotor IE2 and the frequencywill be that of the power source, for example, 400 cycles. One terminalof field winding I14 is connected to ground terminal I'iI while theother terminal of field winding II4 is connected to an authoritypotentiometer I) through a capacitor I3 I. Capacitor I8I is a blockingcapacitor providing an open circuit for any unidirectional voltage whichmight arise in field winding I14. Wiper arm I 82, on potentiometer Iiie,is connected to a grid I33 of tube I84 through lead I85. The position ofthe wiper arm on potentiometer I85 determines the amount of signalvoltage induced in field winding IZ' t which will be fed to tube I84.This will be described in greater detail later in the specification.

Tube I85 has in addition to grid I83, an anode I55, a cathode I31 and afilament, not shown. Cathode It? is connected to ground terminal I11through a resistor lei! which is used to obtain a desired self biasbetween the grid I33 and oathode I81.

The output of tube I 94 is impressed on grid III! of tube I32 by aconnection from anode I85 through capacitor I53 and resistor I94. Thejunction between capacitor I93 and resistor I94 is connected to groundterminal I11 by resistor I95, which is a grid leak resistor.

Tube I92 has in addition to control electrode an anode I95, a cathodeI91 and a filament, not shown. Cathode I91 is connected to groundterminal I'I'I through resistor 283 used to obtain a desired self biasbetween the grid I9I and cathode I82.

The anode voltage supply for tubes I84 and I92 is obtained from fullwave rectifier M by a. connection from the cathode 52, lead 36, chokecoil Iii, leads 55, 2iiI and 262, to the junction of resistors 2&3 and2M, and from there to the respective anodes I86 and I96.

The output of tube I92 is connected to grid 225 of tube 285 by leads 2Mand 2E9, capacitor 2H and lead 2 I2. The output of tube I92 is alsoconnected to a grid 2 I3 of tube 2 Id by leads 2m and 215, capacitor 2H5and lead 2H. It will be seen that the phase of the signal voltagesimpressed on grids 225 and 2I3 are the same since they are taken fromthe same point in the output of amplifier tube I 2.

Tube 25% has, in addition to grid 225, an anode 228, a cathode 22! and afilament, not shown. Tube 22 5 has, in addition to grid 2i3, an anode222, a cathode 223 and a filament, not shown. Cathodes 221 and 223 areconnected to ground terminal 22% through leads 2255 and 226 respectively.

The anode voltage supply for tube 266 is obtained. from transformersecondary 42 through lead 22?. The other end of transformer secondary:22 is connected to ground terminal 232 through resistors 23! and 232. Acapacitor 233 is connected in parallel therewith. The junction betweenresistors 23I and 232 is tied to grid 265 in a feedback circuit throughlead 23%, resistor 235 and lead 236. The anode voltage supply for tube2M is furnished from transformer secondary 43 through lead 23?. Theother terminal of transformer secondary 43 is connected to groundterminal 232 through resistors 262 and 2 I and a capacitor 252 isconnected in parallel with said resistors. The junction betweenresistors 245i and 2 3i is connected to grid 2 I 3 in a feedback circuitthrough lead 223, resistor 22-2 and lead 225. These feedback circuitsare to provide a feedback signal for tubes 2% and 2 I i to maintain thegrids within predetermined limits so that increase in control signalover a desired range Will cause increases in plate current until adesired point of saturation is reached when further increases in inputsignal will cause no increase in tube current.

Capacitors 233 and 242, placed in parallel with resistors 23I and 232and 24.!) and 2 5i respectively, are filter capacitors which by-passalternating currents flowing in the circuit and result in aunidirectional voltage being impressed across these resistors. Theoutput voltage from tube 2% is connected to grid N2 of thyratron H3 in acircuit traced from anode 226 through lead 22?, transformer secondary42, lead 2-66, resistor 2 22, leads 248 and lit and resistor ill to gridM2. The output voltage from tube 2M i impressed on grid I 2t ofthyratron H2! in a circuit traced from anode 222 through lead 23?,transformer secondary 23, lead 252, resistor 25!, leads 252 and I22 andresistor I25 to grid I25. These output voltages will be unidirectionalvoltages.

Tubes 2Il6 and 2M, with their associated components and circuits form analternating current discriminator stage. The tubes, as connected totheir respective secondaries, are adapted to become conductive, with aninput signal present on the grids, on alternate half cycles of the powersupply, with the conduction dependent upon the phasing of the inputsignal to the respective grids. If the phasing of the voltages betweengrid and cathode and anode and cathode of tube 206 is such that thevoltages on both grid and anode with respect to the oathode will be onthe positive portion of the cycle simultaneously, the phasing of thevoltages between grid and cathode and anode and cathode of tube 2M issuch that when the voltage on the grid with respect to the cathode is onthe positive portion of the cycle the voltage on the anode with respectto the cathode is on the negative portion of the cycle. Under thesecircumstances tube 206 will be more conductive on the half cycle duringwhich its anode is positive with respect to its cathode than will tube2M on the following half cycle. As the resultant voltages across therespective output networks for the two tubes will be proportional to theconduction of the tubes, the voltage drop across resistors 235 and 232will be greater than that across resistors 24d and 24!. If the inputsignal voltage applied to the grids 286 and 2 I4 is of the oppositephase with respect to the voltages between anodes and cathodes to thatcondition described above it is obvious that the voltage acrossresistors 249 and 2M will be greater than that across resistors 2M and232. It is thus seen that the voltage drops across resistors 23I and 232and across resistors 256 and 2 are dependent upon the phasing of theinput signal to the grids of tubes 2% and 2M with respect to thevoltages between the anodes and cathodes of the tubes. Further, theright hand terminals of resistors 23! and 242, as seen the drawing,which are connected to the respective anodes, will be more or lessnegative with respect to ground in accordance with the phasing of theinput signal. This is true because, as can be seen in the drawing,resistors 223i and 232 are connected in series, as are resisters 243 and2 1i, with the left hand terminals of resistors 232 and 24! connected toa common ground and the electron fiow through the tubes passing fromcathode to anode, the electron flow will be from right to left acrossthe resistors, resulting in the right hand terminals of resistors 23Iand 242 being negative with respect to ground and by the amount of thevoltage drops across resistors 23! and 232 and across resistors 2 5.3and 24!. This varying negative voltage is used in controlling tubes H3and I2I, as will be understood from the discussion following.

When either tube 206 or tube 2M conducts, a negative output voltage isapplied on grid H2 or I253 of thyratron H3 or I2l through resistors 24'!and Ill or 25I and I25 to tend to cause that thyratron to becomenonoonductive. Upon conduction of tube I2, the output voltage from tubeI2 is applied to grid H2 of thyratron H3 by a circuit traced fromcathode 84 through lead lid, resistor H5, lead H6, and resistor II! togrid H2. The output voltage from tube 295, upon conduction thereof, isapplied to grid M2 by a circuit traced from anode 222 through lead 2?,transformer secondary 42, lead .246, resistor 22?, leads 243 and H6, andresistor ill to grid H2. Thus, both a positive and a negative signal areseen to be impressed upon grid H2 when both tubes 72 and 28B conductsimultaneously. Resistors H5 and 241 have been put into the circuits toact as isolating resistors to prevent signals from tube 12 fromafiecting operation of tube 206 and vice versa. Resistors I23 and 223iin like manner serve as isolating resistors for tubes IT and 2I4'.

Let it be assumed that there is a signal output from the compass I6,due. to a displacement of rotor I6 from the null point, which is of sucha phase as to cause tube 72 to conduct on alternate half cycles. Thatis, the grid H of tube I2 is positive during the same half cycle asanode 83. With this phasing, tube I I does not conduct because, duringthose half cycles at which grid I6 is positive, anode 85 is negative andon the alternate half cycles, when anode 35 is positive, grid I6 isnegative and there is, therefore, no conduction during the entire cycle.Let it also be assumed that this apparatus has been operating for sometime and that movable contact I45 is making contact with fixed contactsI43 and I44 to complete the connection to ground from the cathodes I2!and I3I of thyratrons I I3 and I 2|. With tube I2 conducting duringalternate half cycles a unidirectional voltage is developed acrossresistors 96 and 9I, which voltage is filtered by capacitor 92. Thecathode 84 of tube I2 is positive with respect to ground terminal 81 andtherefore a positive signal is impressed on grid II2 of thyratron H3.

A unidirectional voltage of positive polarity is now impressed on gridH2 of thyratron H3. On the half cycle of the periodically varying powersupply, when anode I26 of thyratron H3 is positive, relay coil I33 isenergized and capacitor I34 in parallel with relay coil I33 is charged.This charge on capacitor I34 leaks off through relay coil I33 during thefollowing half cycle to keepthe relay energized to maintain movablecontact I4I closed against fixed contacts I56 and NH. With movablecontact I 41 making contact with fixed contacts I56 and I5! the aligningmotor I6I is energized as has been explained above. Rotor I62 ofaligning motor I6I begins to rotate, picking up speed with increasedtime of energization of the field Winding. The rotor I16 of velocitygenerator III driven by rotor I62 commences to rotate at the same rateas the rotor. A gradually increasing alternating voltage is thereforeinduced in field winding I14 to cause an increasing alternating voltageto be impressed across potentiometer I36. This signal is amplifiedthrough tubes I84 and I92 and is impressed on grid 265 of tube 266 as avoltage which is in phase with the voltage on anode 226 of tube 266causing tube 265 to conduct. At the same time aligning motor rotor I62will be rotating receiver rotor I9 with respect to receiver stator I8 inthe compass I6 to reduce the signal output from the compass to the tube2I.

When the voltage on grid 265 is in phase with the voltage on anode 226the voltage on grid N3 is out of phase with the voltage on anode 222 oftube 2I4 because the voltages on the anodes are in opposition to eachother while the voltages on the grids are in phase. Therefore tube 2Mdoes not conduct. During. the alternate half cycles when tube 265conducts a voltage drop is developed across resistors 23I and 232 and acharge is built. up across capacitor 233 which leaks ofi throughresistors 23I and 232. during the half cycles when tube 266 is notconducting. The voltage on the junction of resistor 237i and transformersecondary 42 is negative with respect to ground and therefore a negativevoltage is impressed upon grid I I 2 of thyratron I I3 to combine withthe positive voltage impressed on grid II2 by tube I2.

AS h pe d o the oto 1w Velocity erator I'II increases, increasing thevoltage across potentiometer I86, the voltage on grid 265 increases in apositive direction to increase the conduction of tube 266 to cause anincreasingly negative voltage to be impressed upon grid II2 to graduallyovercome the positive voltage which is being impressed upon this grid bytube I2. At the same time the positive voltage being impressed on the,grid II2 by tube I2 is decreasing, assuming the signal output from coilsI6 remains the same, because motor I6I is connected to receiver rotor I9through mechanicalconnection I78 and operation of motor I 6I causesrotation of receiver rotor I9 in such a direction as to decrease thesignal induced into rotor I9 by stator I8 and thus decrease the signalfrom the compass to the amplifier. When the negative voltage on gridII2, due to the conduction of tube 266 overcomes the positive voltage ongrid I I2, due to conduction of tube I2, tube H3 stops conducting andrelay coil I33 is deenergized, causing movable contact I41 to breakcontact with fixed contacts I56 and I5! to deenergize the circuit tofield windings I63 and I64 of aligning motor I6I. When this happens therotor I62 of the motor slows down as does the rotor I16 of the velocitygenerator. This causes the induced voltage in field winding I14 of thevelocity generator to become less and less, reducing the voltage acrosspotentiometer I86. This reduced potential being impressed on grid 265 oftube 266 causes reduced conduction of tube 266 to lessen the magnitudeof the negative voltage impressed by this tube on grid I I2 of thethyratron.

When the velocity generator signal decreases, its magnitude will tendto. go to a value that is less than the unbalance signal from thecompass I6. This will result in the negative voltage from tube 266becoming less in magnitude than the positive voltage from tube I2. Whenthe negative voltage on grid II2 due to tube 266 becomes smaller inmagnitude than the. positive voltage on grid H2, due to tube 72, thethyratron H3 again conducts to again close the contact I4! with contactsI56 and I5I to in turn energize the field windings of the aligning motorand cause the rotor I62 to again begin rotating and turn the rotor II6of the velocity generator. This in turn builds up the induced voltage infield winding I'M of the velocity generator which operates to increasethe negative signal on grid II2 of the thyratron to cause the thyratronto again move to cutoif. This operation results in a pecking action onthe part of the relay and the resultant energization of the motor causesthe rotor I9 to be moved to a null position where there is no outputfrom the rotor I9.

If the direction of unbalance in compass I6 were opposite the unbalanceassumed above, the phase of the signal voltage from the compass would bereversed, causing operation of tubes I1 and I2I. Operation of tube I2Ienergizes relay coil I3! to close contact I52 against contacts I53 andI54 and energizes motor I6I. This results in the velocity generatorrotor I16 and receiver rotor I9 being driven in the opposite directionby motor I6I. Tube 2I4 will now be conductive rather than tube 266because of the reverse phasing of the output from the velocitygenerator. The output voltage from tube 2I4 is compared with that oftube 17 to control tube I2I. As before, the motor I6I will drive therotor I9 into a null position by the controlling of the energization ofrelay I33. This control, as the null point 11 is approached will besimilar to the pecking action described above. If the wiper arm 532 ofthe authority potentiometer H39 were moved toward the grounded end ofthe potentiometer, a much smaller voltage from the field winding iii. ofvelocity generator ill would be applied to the amplifier. Under thissituation, the reiay which is energized by a particular unbalance signalwould remain energized for a longer period of time until the signal fromthe compass were reduced sufficiently that the velocity generator signalvoltage would overcome the compass signal voltage on either of i ii orWill.

If the wiper arm as: were moved to the end of potentiometer l iiconnected to ground ill, so that there would be no velocity generatorsignal applied to the amplifier, there would be no pecking action at alland the system would hunt around a balance point due to the inertia ofthe apparatus. If wiper arm i822 were moved to the opposite end ofpotentiometer i821 from ground ill the pecking action would be veryrapid be cause the induced voltage from the velocity generator pic zedoif by wiper i82 would rise much more rapidly than if the wiper werenear the ground end of potentiometer MG.

Receiver stator it may be mounted on a directional gyro on which aprecession motor is mounted. Once rotor it has been rotated by aligningmotor Mil so that compass i8 is aligned the aligning motor may beswitched out of the circuit and the precession motor connected into thecircuit so as to be controlled by the signal through the channel of theamplifier operated by compass it.

From the foregoing it will be seen that there has been provided anapparatus for reversibly controlling a motor operating at a firstfrequency when the controlling signals therefor are of the firstfrequency and of a different frequency. It will also be seen that anamplifier for reversibly energizing a controlled motor has been providedwhen that amplifier is energized by a power source of a first frequencyand the control signals therefor are of the first and of a secondfrequency.

Though not intended to be interpreted as the only values of componentswhich will operate in this circuit the following values constitute oneset which were found to have operated satisfactorily.

Resistors N, 36, 96, 9?, H5, lil, i223, i252,

I56, i557, led, I555, 235, 2M, 2M, i

megohms l Resistors 25, wt kilohms 2.2 Resistors 3d, 2% do 6.8 Resistors65, it, 9i, 9d, 263, 2M do 47o Resistors 98, 93 do i? Resistors 23H, 2%do 270 Resistors 232, 2 H do 100 Resistor 56 do 3.5 Resistor 62 do 20Potentiometer E80 do 1 Capacitors 26, 15, ti, I93, 2M, 2M

microfarads 0.01 Capacitors 35, e2, 95, 233, 2 32 do 0.25 Capacitors itl, Hi6 do 0.02 Capacitors i3 3, Mil do 2 Capacitors 51, M do 10Capacitor I55 do 0.07 Capacitor i8! do 0.23

It is to be understood that various modifications may readily appear toone skilled in the art. It is therefore intended that the scope of theinvention be limited only by the appended claims, in which I claim:

I claim as my invention:

1. An electronic circuit having in combination: a source of voltage; asignal voltage; a first pair of electron discharge devices each havingan anode, a cathode and a control electrode; means applying said signalvoltage between said control electrodes and said cathodes; means placingvoltages from said source between the anodes and cathodes of saiddevices; a second pair of dis charge devices each having an anode, acathode and a control electrode; means connecting said anodes andcathodes of said second pair of discharge devices across said source;means connecting the cathodes of said first pair of discharge devices tothe control electrodes of said second pair of discharge devices; a thirdpair of electron discharge devices each having an anode, a cathode and acontrol electrode; a control device connected to the anode of each ofsaid second pair of discharge devices; a circuit, said circuitcomprising a motor that is energized upon the operation of one of saidcontrol devices, speed responsive means connected to said motor, saidspeed responsive means applying a voltage between the control electrodesand cathodes of said third pair of electron discharge devices; meansconnecting the anodes and cathodes of said third pair of electrondischarge devices across said voltage source; and means connecting theanodes of said third pair of electron discharge devices to the controlelectrodes of said second pair of discharge devices such that thedifierence be tween the output voltages of said first pair of dischargedevices and said third pair of discharge devices when applied betweensaid control elec trodes and cathodes of a second pair of dischargedevices determines the effective voltage between said control electrodesand cathodes to cause intermittent operation of either of the dischargedevices in said second pair depending upon the signal voltage.

2. An electronic circuit having in combination: a source of alternatingvoltage of a first frequency; a signal voltage of a second frequency; afirst pair of electron discharge devices each having an anode, a cathodeand a control electrode; means applying said signal voltage to saidcontrol electrodes such that the voltages on said control electrodes arein phase; means placing voltages from said source on said anodes of saiddevices such that the voltages on said anodes are in phase opposition; asecond pair of discharge devices each having an anode, a cathode and acontrol electrode; means connecting said anodes of said second pair ofdischarge devices to said source such that the voltages on said anodesare in phase; means connecting the cathodes of said first pair ofdischarge devices to the control electrodes of said second pair ofdischarge devices; a third pair of electron discharge devices eachhaving an anode, a cathode and a control electrode; a control deviceconnected to the anode of each of said second pair of discharge devices;a circuit, said circuit comprising a motor that is energized upon theoperation of one of said control devices, speed responsive meansconnected to said motor, said speed responsive means applying analternating voltage of said first frequency on the control electrodes ofsaid third pair of electron discharge devices; means connecting theanodes of said third pair of electron discharge devices to said voltagesource Such that the voltages on said anodes are in phase'opposition;and means connecting the anodes of said third pair of electron dischargedevices tothe control electrodes of said second pair of dischargedevices such that the difference between the output voltages of saidfirst pair of dischargedevices and said third pair of discharge deviceswhen applied to said control electrodes determines the efiective voltageon said control electrodes to cause intermittent operation of either ofsaidsecond pair of discharge devices depending" upon the signal voltage.e

3. An electronic circuit having in combination: a source of alternatingvoltage; a signal voltage of twice the frequency of said source; a firstpair of electron discharge devices each having an anode, a cathode and acontrol electrode; applying said signal voltage to said controlelectrodes such that the voltages on said control electrodes are inphase; a full wave rectifier supplied by said source; atransformer;'means connecting said rectifier output through saidtransformer to produce a voltage of twice the frequency of said source;means connecting the output of said transformer to the anodes of saiddevices such that the voltages'on said'anodes are in phase opposition;means, including said first pair of discharge devices forconverting'said signal voltage to unidirectional voltage; asecond pairof discharge devices each having an anode, a cathode and a controlelectrode; means'connecting said anodes of said second pair of dischargedevices-to said source such that the voltageisonsaid anodes are inphase; means connecting-the cathodes of said first pair ofdischarge-devices'to the control erectrodes of said second span-"ofdischargedevices; a third pair of electron discharge devices each havingan anode, a cathode and a control el ctrode; a control device connectedto the anode of each of said second pair of discharge devices; acircuit, said circuit comprising a motor that is energized upon theoperation of one of said control devices, speed responsive meansconnected to said motor, said speed responsive means applying analternating voltage on the control electrodes of said third pair ofelectron discharge devices; means connecting the anodes of said thirdpair of electron discharge devices to said voltage source such thatthevoltages on said anodes are in phase opposition; means, includingthird pair of electron discharge devices, for converting the outputvoltage from said-third pair of electron discharge devices tounidirectional voltage; and means connecting the anodes of said thirdpair of electron discharge devices to the control electrodes of saidsecond pair of discharge devices such that the difference between theoutput voltages of said first pair of discharge devices and said thirdpair'of discharge devices when applied to said control electrodesdetermines the effective voltage on said control electrodes to causeintermittent operation of either of the discharge devices of said secondpair depending upon the signal voltage.

4. An electronic circuit having in combination: source of alternatingvoltage; an alternating signal voltage; a first pair of electrondischarge devices each having an anode, a cathode and a controlelectrode; means applying said signal voltage to said control electrodessuch that the voltages on said control electrodes are in phase; meansconnecting said source of voltage to said anodes such that the voltageson said anodes are in phase opposition; a resistor in the cathodecircuit of each discharge device; a capacitor connected across each ofsaid resistors such that the voltage across said resistors uponoperation of said devices is undirectional voltage; a pair of gaseousdischarge devices each having an anode, a cathode and a controlelectrode; means connecting said anodes of said gaseous dischargedevices to said-source such that the voltages on said anodes are inphase; means connecting the cathodes of saidfirst'pair of dischargedevices to the control electrodes of said gaseous discharge devices; asecond pair of electron discharge devices each having an anode, acathode and a control electrode; a control device connected to the anodeof each of said gaseous discharge devices; acircuit, operated uponenergization of one of said control devices, which places an alternatingvoltage on the control electrodes of said second pair of electrondischarge devices; means con necting the'anodes of said second pair ofelectron discharge devices to said voltage source such that the voltageson'said anodes are in phase opposition; a resistor in the anode circuitof each of' said second pair of electron discharge devices; a capacitorconnected across each of said resisters in the anode circuits of saidsecond pair or" electron discharge devices such that the voltage acrosssaid resistors upon operation of said de-- vices is unidirectionalvoltage; and means connecting the anodes of said second pair of electrondischarge devices to the control electrodes of said gaseous dischargedevices such that the difference between the two unidirectional voltageson said control electrodes determines the efiective voltage on saidcontrol electrodes to cause intermittent operation of either of saidgaseous discharge devices depending upon the signal voltage.

5. An electronic circuit having in combination: a source of alternatingvoltage; a signal voltage of twice the frequency of said source; a firstpair of electron discharge devices each having an anode, a cathode and acontrol electrode; means applying said signal voltage to said controlelectrodes such that the voltages on said control electrodes are inphase; a full Wave rectifier supplied by said source; a transformer;means connecting said rectifier output through said transformer toproduce a voltage of twice the frequency of said source; meansconnecting the output of said transformer to the anodes of said devicesuch that the voltages on said anodes are in phase opposition; aresistor in the cathode circuit of each discharge device; a capacitorconnected across each of said resistors such that the voltage acrosssaid resistors upon operation of said devices is unidirectional voltage;a pair of gaseous discharge devices each having an anode, a cathode anda control electrode; means connecting said anodes of said gaseousdischarge devices to said source such that the voltages on said anodesare in phase; means connecting the cathodes of said first pair ofdischarge devices to the control electrodes of said gaseous dischargedevices; a second pair of electron discharge devices each having ananode, a cathode and a control electrode; a control device connected tothe anode of each of said gaseou discharge devices; a circuit, operatedupon energization of one of said control devices, which places analternating voltage on the control electrodes of said second pair ofelectron discharge devices; means connecting the anodes of said secondpair of electron discharge devices to said voltage source such that thevoltages on said anodes are in phase opposition; a resistor in the anodecircuit of each of 'said second pair of electron discharge devices; acapacitor connected across each of said resistors in the anode circuitsa shole of said second pair of electron discharge devices such that thevoltage across said resistors upon operation of said devices isunidirectional Voltage and means connecting the anodes of said secondpair of electron discharge devices to the control electrodes of saidgaseous discharge devices such that the difference between the twounidirectional voltages on said control electrodes determines theeffective voltage on said control electrodes to cause intermittentoperation of either of said gaseous discharge devices depending upon thesignal voltage.

6. An electronic circuit having in combination: a source of alternatingvoltage; a signal voltage of twice the frequency of said source; a firstpair of" electron discharge devices each having an anode, a cathode anda control electrode; means applying said signal voltage to said controlelectrodes such that the voltages on said control electrodes are inphase; a full wave rectifier supplied by said source; a transformer;means connecting said rectifier output through said transformer toproduce a voltage of twice the frequency of said source; meansconnecting the output of said transformer to the anodes of said devicessuch that the voltages on said anodes are in phase opposition; aresistor in the cathode circuit of each discharge device; a capacitorconnected across each of said resistors such that the voltage acrosssaid resistors upon operation of said devices is unidirectional voltage;a bias voltage on each of said control electrodes obtained byelectrically connecting said control electrodes to the cathod circuitsof the respective discharge de' vices; a pair of gaseous dischargedevices each having an anode, a cathode and a control electrode; meansconnecting said anodes of said gaseous discharge devices to said sourcesuch that the voltages on said anodes are in phase; means connecting thecathodes of said first pair of discharge devices to the controlelectrodes of said gaseous discharge devices; a second pair of electrondischarge devices each having an anode, a cathode and a controlelectrode; a control device connected to the anode of each of saidgaseous discharge devices; a circiut, operated upon energization of oneof said control devices, which places an alternating voltage on thecontrol electrodes of said second pair of electron discharge devices;means connecting the anodes of said second pair of electron dischargedevices to said voltag source such that the voltages on said anodes arein phase opposition; a resistor in the anode circuit of each of saidsecond pair of electron discharge devices; a capacitor connected acrosseach of said resistors in the anode circuits of said second pair ofelectron discharge devices such that the voltage across said resistorsupon operation of said devices is unidirectional voltage; and meansconnecting the anodes of said second pair of electron discharge devicesto the control electrode of said gaseous discharge devices such that thedifference between the two unidirectional voltages on, said controlelectrodes determines the effective voltage on said control electrodesto cause intermittent operation of either of said gaseous dischargedevices depending upon the signal voltage.

'7. An electronic circuit having in combination: a source of voltage; asignal voltage; a first electron discharge device having an anode, acathode and a control electrode; means applying said signal voltage tosaid control electrode; means placing a voltage from said source on theanode of said device; a second discharge device having an anode,acathode and a control electrode; means connecting the anode of saidsecond discharge device to said source; means connecting the oathode ofsaid first discharge device to the control electrode of said seconddischarge device; a third electron discharge device having an anode, acathode and a control electrode; a control device connected to the anodeof said second discharge device; a circuit, said circuit comprising amotor that is energized upon the operation of said control device, speedresponsive means connected to said motor, said speed responsive meansapplying a voltage on the control electrode of said third electrondischarge device; means connecting the anode of said third electrondischarge device to said voltage source; and means connecting the anodeof said third electron discharge device to the control electrode of saidsecond discharge device such that the diilerence between the outputvoltages of said first discharge device and said third discharge devicewhen applied to said control electrode determines the effective voltageon said control electrode to cause intermittent operation of said seconddischarge device.

8. An electronic circuit having in combination: a source of alternatingvoltages; a signal voltage of twice the frequency of said source; afirst electron discharge device having an anode, a cathode and a controlelectrode; means applying said signal voltage to said control electrode;a full wave rectifier supplied by said source; a transformer; meansconnecting said rectifier output through said transformer to produce avoltage of twice the frequency of said source; means connecting theoutput-of said transformer to the anode of said device; means, includingsaid first discharge device for converting said signal voltage tounidirectional voltage; a second discharge device having an anode, acathode and a control electrode;

means connecting said anode of said second discharge device to saidsource; means connecting the cathode of said first discharge device tothe control electrode of said second discharge device; a third electrondischarge device having an anode, a cathode and a control electrode; acontrol device connected to the anode of said second discharge device; acircuit, said circuit comprising a motor that is energized upon theoperation of said control device, speed responsive means connected tosaid motor, said speed responsive means applying an alternating voltageon the control electrode of said third electron discharge device; meansconnecting the anode of said third electron discharge device to saidvoltage source;

means, including said third electron discharge device, for convertingthe output voltage from said third electron discharge device tounidirectional voltage; and means connecting the anode of said thirdelectron discharge device to the control electrode of said seconddischarge device such that the difference between the two voltages onsaid control electrode determines the effective voltage on said controlelectrode to cause intermittent operation of said second dischargedevice.

9. An electronic circuit having in combination: a source of alternatingvoltage; a signal voltage of twice the frequency of said source; a firstelectron discharge device having an anode, a cathode and a controlelectrode; means applying said sig nal voltage to said controlelectrode; a full wave rectifier supplied by said source; a transformer;means connecting said rectifier output through said transformer toproduce a voltage of twice the frequency of said source; meansconnecting the output of said transformer to the anode of said device; aresistor in the cathode circuit of said discharge device; a capacitorconnected across said resistor such: that the voltage acrosssaid'resistor upon operation of said device is unidirectional voitage; agaseous discharge device having an anode, a cathode and a controlelectrode; means connecting said anode of said gaseous discharge deviceto said source; means connecting the cathode of said first dischargedevice to the control electrode of said gaseous discharge device; asecond electron discharge device having an anode, a cathode and acontrol electrode; a control device connected to theanode of saidgaseous discharge device; a circuit, operated? upon .energization ofsaid control device, which places an alternating voltage on the controlelectrode of said second electron discharge device; means connecting theanode of said second electron discharge device to: said voltage source;a resistor in the anode circuit or said second electron dischargedevice'; a capacitor connected across said resistor in the anode circuitof said second electron discharge device such that the voltage acrosssaid resistor upon operation of said device is unidirectional voltage;and means connecting the anode of said second electron discharge deviceto the control electrode of said gaseous discharge device such that thediiference between the two unidirectional voltages on said controlelectrode determines the eiiective voltage on said" control electrode tocause intermittent operation of said gaseous discharge device.

10. Motor control apparatus, comprising in combination: a source ofpower varying at a first periodic rate; motor means adapted to' beenergized by a source of power varying at said first periodic rate; acondition responsive device adapted to indicate the need for operationof said motor means, said device having an output signal which varies ata second periodic rate; motor speed responsive means connected: to saidmotor means, said speed responsive means having an output signal which:varies at said first periodic rate; combiningmeans including rectifyingmeans for algebraically adding said signals to form a resultantunidirectional signal that has a characteristic dependent upon therelative values of said signals; and means associated with saidcombining means reversibly controlling the energization of said motormeans from said source of power in accordance with said resultantunidirectional signal.

11. Motor control apparatus, comprising in combination: a sourceof powervarying at a first periodic rate; motor means adapted to be energized'by a source of power varying at said first periodic rate; aconditionresponsive device adapted to indicatethe need for operation ofsaid motor means, said device having an output signal which varies at asecond periodic rate; motor speed responsive means connected to saidmotor means, said speed responsive means having an output signal whichvaries at said first periodic rate; combining means including rectifyingmeans for algebraically adding said signals to form a resultantunidirectional signal that has a magnitude and polarity dependent uponthe difference of the relative values of said signals; and meansassociated with said combining means reversibly controlling theenergization of said motor means from said source of power in accordancewith said resultant unidirectional signal, said motor means beingoperative upon 18 said resultant unidirectional signal reaching, apredetermined value.

12. Motor control apparatus, comprising in combination: a source ofpower varying at a first periodic rate; motor means adapted to beenergized by a source of power varying at said first periodic rate; acondition responsive device adapted to indicate the need for operationof said motor means, said device having an output signal -which variesat a second periodic rate; motor speed responsive means connected tosaid motor means, said speed responsive means having an output signalwhich varies at said first periodic rate; means for rectifying andcombining: said signals to form a combined unidirectional signal thathas a characteristic dependent upon the relative values of said.signals; electronic means for reversibly controlling the energization ofsaid motor means from said source of power; and circuit meansconnecting. said combined unidirectional signal to said electronic meansto eifect the controlling action of said motor means.

13. Motor control apparatus, comprising in combination: a source ofpower varying at a first periodic rate; motor means adapted to beenergized by a source of power varying at said first periodic rate; acompass adapted to indicate the need for operation of said motor mean-s,said compass having an output signal which varies at a second periodicrate; motor speed responsive means connected to said motor means, saidspeed responsive means having an output signal which varies at saidfirst periodic rate; means for rectifying and combining said signals toform a combined unidirectional signal that has a magnitude and sensedependent upon the relative values and phases of. said signals; biasedelectronic means for reversibly controlling the energization of saidmotor means from said source of power; and circuit means connecting saidcombined unidirectional signal to said biased electronic means to offsetthe controlling action of said motor means in accordance with themagnitude and senseof said combined unidirectional signal.

14. An electronic circuit having in combination: a source of supplyvoltage, saidsource having a frequency of afirst value; a source ofsignal voltage, said signal source having a frequency of a second highervalue; a pair of discharge devices each having an anode, a cathode, anda control electrode; means connecting said anodes and said cathodesacross said supply voltage; a control device in the anode: circuit ofeach of said discharge devices, said control. device being eifective torender a motor operative; means converti-ngv said signal voltage to aunidirectional voltage; the magnitude and direction of which depend uponthe magnitude and phase of said signal voltage; means impressing said:converted signal voltage between the control electrodes and cathodes ofsaid discharge devices; motor speed responsive means actuated uponoperation of one or the other of said control devices, said speedresponsive means having an output voltage the frequency of which is thesame as said first value; means converting said output voltage to aunidirectional voltage, the magnitude and direction of which depend uponthe magnitude and phase of said output voltage; and means connectingsaid converted output voltage in opposition to said converted signalvoltage between the control electrodes and cathodes of said dischargedevices such that the difference of the two voltages across the controlelectrodes and cathodes determines 1 9 the effective voltage betweensaid control electrodes and cathodes to cause intermittent pulsations ofeither of said discharge devices depending upon the signal voltage.

15. An electronic circuit having in combination: a source of alternatingsupply voltage, said source having a frequency of a first value; asource of signal voltage of a frequency other than that of said supplyvoltage; a pair of discharge devices each having an anode, a cathode anda control electrode; means connecting said anodes and said cathodesacross said supply voltage such that the voltages on said anodes withrespect to said cathodes are of the same phase; means converting saidsignal voltage to unidirectional voltage, the magnitude and direction ofwhich depend upon the magnitude and phase of said signal voltage; meansimpressing said converted signal voltage between said control electrodesand said cathodes; a control device in the anode circuit of each of saiddischarge devices, said control devices being efi'ective to render amotor operative; motor speed responsive means having an output signalwhich has a frequency of said first value actuated upon operation of oneof said control devices; means converting said signal voltage from saidmotor speed responsive means to a unidirectional voltage of oppositepolarity of said signal converted voltage; and means impressing saidlast named unidirectional voltage between the control electrodes andcathodes of said discharge devices such that the difference of the twounidirectional voltages across the control electrodes and cathodesdetermines the effective voltage between said control electrodes andsaid cathodes to cause intermittent pulsations of either of saiddischarge devices depending upon the signal voltage.

16. An electronic circuit having in combination: a source of alternatingsupply voltage; a source of signal voltage of a frequency other thanthat of said supply voltage; a pair of discharge devices each having ananode, a cathode and a control electrode; means connecting said anodesand said cathodes across said supply voltage; a control device in theanode circuit of each of said discharge devices; means converting saidsignal voltage to unidirectional voltage, the magnitude and direction ofwhich depend upon the magnitude and phase of said signal voltage; meansimpressing said converted signal voltage between said control electrodesand said cathodes to cause energization of only one of said dischargedevices at a time; means energizing the control device in the anodecircuit of the discharge device which is energized, said control devicesbeing effective to render a motor operative; motor speed responsivemeans, actuated upon energization of one of said control devices andhaving an output signal which alternates at a frequency which is thesame as that of said source of supply; means converting said outputsignal of said motor speed responsive means to a unidirectional voltageof opposite polarity of said converted signal voltage and of graduallyincreasing magnitude; and means impressing said last namedunidirectional voltage between the control electrode and cathode of theenergized discharge device to eventually overcome said converted signalvoltage and cause de-energization of said discharge device and saidcontrol device, the interaction of said unidirectional voltages causingintermittent energization of the discharge device and control device.

17. An electronic circuit having in combination: a source of alternatingsupply voltage, said source having a frequency of a first value; asource of signal voltage having a frequency of a second higher value; adischarge device having an anode, a cathode and a control electrode;means connecting said anode to said supply voltage; a control device inthe anode circuit of said discharge device; means converting said signalvoltage to unidirectional voltage, the magnitude and direction of whichdepends upon the magnitude and phase of said signal voltage; meansimpressing said converted signal voltage on said control electrode;means energizing the control device in the anode circuit uponenergization of the discharge device; electrical circuit meanscontrolled by the energization of said control device and having analternating signal which alternates at the same frequency as said supplyvoltage; means converting said alternating signal from said electricalcircuit means to a unidirectional voltage of opposite polarity of saidconverted signal voltage and of gradually increasing magnitude; andmeans impressing said last named unidirectional voltage on the controlelectrode of the energized discharge device to eventually overcome saidconverted signal voltage and cause deenergization of said dischargedevice and said control device, the interaction of said unidirectionalvoltages resulting in intermittent operation of the discharge device andcontrol device.

ROBERT R. CHAPMAN.

References Cited in the file of this patent UNITED STATES PATENTS Date

